Radio frequency identification (RFID) systems offer the possibility of inexpensive and efficient management of goods, with applications in inventory control and retail checkout. Each item in an inventory, for example in a retail store or a warehouse, may be equipped with an RFID tag, that is, a tag containing an RFID emitter that supplies information about the product to an RFID reader. The information may include product identification information, such as manufacturer and item identifiers, similar to those provided by a standard universal product code bar code. The information may also include a unique serial number or other unique identifier, so that each individual item may be easily identified by a reader or readers and the movements of identified items may be tracked. Typical RFID readers broadcast an RF signal. Tags within the range of the reader return a signal to the reader, typically in the form of modulated backscatter of the signal emitted by the reader.
A reader may be placed at a desired inventory control point, such as a retail checkout station or an entrance to or exit of a retail location, warehouse or other area where goods are located. Tags coming within range of the reader are powered by the reader's RF signal and transmit tag information which is detected by the reader. The information detected by the reader may be used in operations, such as purchase transactions, involving the item or items whose information was detected. Such operations may include entry of a product into a transaction or logging the entry of an item into or the exit of an item from a retail location, warehouse or other controlled environment.
The use of RFID devices for management of goods offers possibilities of fast and efficient control of goods. For example, a customer might bring a cart full of goods bearing RFID tags to a terminal, which would include a reader receiving product identification information for each product. The terminal would retrieve product information, such as price or descriptive information for each product. The terminal would then enter product information for each product into a transaction and present the customer with a list of goods in the transaction and a transaction total. The customer would then tender payment, the transaction would be recorded and the goods would be removed from the retailer's inventory records.
In another application, a warehouse inventory could be continuously updated by one or more RFID readers located in the warehouse and continually sensing RFID signals from goods located in the warehouse. An RFID reader located at an entry or exit point of a location could record the passage of goods through that location, and could secure the entry or exit point to prevent the exit of an item if the item was not properly entered into the transaction.
The use of RFID tags for management of goods can be expected to allow for a significant reduction in the labor required to enter transactions and to prevent the unauthorized removal of goods. If each item transmits an identifying code that can be detected by a reader, tracking and control of the item may be performed automatically. However, many customers have serious privacy concerns at the prospect of a tag that can transmit identifying information at a considerable distance from the tag. The use of such tags raises a possibility that goods owned by a customer could be identified by someone who had no legitimate need for the information. It is possible that RFID product identification could be used in highly intrusive ways. For example, a marketer or other person could conceivably install an RFID reader in a public place, and identify goods owned by unknowing passersby. If unaddressed, privacy concerns might seriously inhibit customer acceptance of retail use of RFID systems.
For best and most versatile use, an RFID tag used in a retail environment should be able to communicate information over a fairly great distance, at least several feet or perhaps tens of feet. Such communication ranges allow for relatively wide coverage for a reader used for transactions or security and allow for relatively unobtrusive placement of readers, for example in a relatively high ceiling. However, after a product has been paid for and left the retail establishment, the retailer no longer needs to track or monitor the product, and the product does not need to be able to communicate over such distances.
There exists, therefore, a need for systems and techniques for RFID communication that allow for an RFID tag to be disabled, or its communication range reduced, when the tracking or monitoring of a product associated with the tag is no longer required.